France's civil aviation authority is predicting major disruptions to scheduled flights to and from French airports on Thursday during nationwide strikes.
An official at the authority says it is likely to trigger procedures under a French law that requires at least a minimum number of air traffic controllers to show up for work in times of strikes.
Under the strike procedure, at least 30% of flights would have to be guaranteed.
Six unions representing the controllers have urged members to join the walkout.
The strike is designed to register concerns about jobs, salaries, purchasing power and benefits amid the global economic crisis.
Transport workers and teachers are expected to take part.